1. Field of the Invention
The present invention generally relates to a scroll-type compressor, and more particularly to a lubricating apparatus for such a scroll-type compressor in which a thrust bearing surface formed on a main frame is supplied with a lubricant, thereby making it possible to support the thrust of an orbiting scroll of the compressor without being provided with a conventional thrust bearing.
2. Description of the Prior Art
As shown in FIG. 1, which shows a conventional scroll-type compressor for compressing, expanding or pumping fluids, for example, a refrigerant gas, the scroll-type compressor is provided with an airtight shell 1, a compressing part 2 and a driving motor part 3, each being enclosed in the shell 1. In addition, a fluid passage for guiding the low pressure fluid, which is subjected to be compressed, toward compression chambers 13 in the compressing part 2 is provided to the compressor. The fluid passage includes a suction pipe 4 formed as penetrating a side wall of the shell 1 and communicating with an external device, for example, an evaporator(not shown) of a refrigerator. On the other hand, there is a discharge pipe 14 provided at an upper end of the compressor in order to guide the compressed fluid of high pressure from the compression chambers 13 to another external device, for example, a condenser(now shown) of the refrigerator.
The compressing part 2 generally comprises a stationary scroll 5, an orbiting scroll 6 being interleaved with the stationary scroll 5, a crankshaft 7 for driving the orbiting scroll 6 in order to cause the scroll 6 to orbit, a balance weight 8 for supporting the eccentric rotation movement of the crankshaft 7, and a main frame 9 for supporting the crankshaft 7 and also receiving the orbiting scroll 6. There is provided a thrust bearing 10 for supporting the orbital motion of the orbiting scroll 6.
The stationary scroll 5 is integrally provided with a wrap 5a having a convolution in the form of an involute or a combination of involutes and arcs, while the orbiting scroll 6 is integrally provided with a wrap 6a having the same shape as that of the wrap 5a of the stationary scroll 5 but with the opposite direction of convolution. The wraps 5a and 6a of the scrolls 5 and 6 are interleaved with each other in order to define the compression chambers 13 therebetween.
Additionally, an Oldham coupling 11 is disposed between the orbiting scroll 6 and the main frame 9, thereby efficiently restraining the orbiting scroll 6 from freely rotating. The crankshaft 7 has at the upper end thereof an eccentric shaft pin 7a which is connected to a downwardly extending hollow shaft of the orbiting scroll 6 by means of an eccentric bushing 12 interposed therebetween. Thus, upon being driven by the crankshaft 7, the orbiting scroll 6 performs orbital motion about a point without rotation, thereby progressively decreasing the volumes of the compression chambers 13 defined by the wraps 5a and 6a, thus compressing the fluid in the chambers 13. Upon being compressed, the compressed fluid in the chambers 13 is discharged from the compressor to the outside through the discharge pipe 14.
On the other hand, the driving motor part 3 comprises a stator 15 which is secured to the inner wall of the shell 1, and a rotor 16 which is secured to the crankshaft 7. There is provided, at the lower part of the compressor, a lubricant reservoir 17 for containing the lubricant therein. An oil pump 18 is provided to the lower end of the crankshaft 7 so that as the crankshaft 7 rotates, the lubricant in the reservoir 17 is upwardly pumped by the oil pump 18 in order to be supplied to respective sliding contact parts of the compressor.
As described above, the known scroll-type compressor needs to be provided with the thrust bearing 10 for supporting the thrust generated by the relative motion between the stationary and orbiting scrolls 5 and 6 as the orbiting scroll 6 performs the orbital motion thereof in order to compress the fluid in the compression chambers 13 between the stationary and orbiting wraps 5a and 6a.
In result, the known scroll-type compressors each has disadvantage in that it is obliged to include an auxiliary thrust bearing for supporting the thrust generated by the relative motion between the stationary and orbiting scrolls during the compression of the fluid, thereby causing an additional designing process for the thrust bearing to be needed, and the manufacturing cost to be considerably increased and also the productivity to be deteriorated. In addition, the necessity of the thrust bearing in the compressor results in uneasiness in assembling the compressor and also an auxiliary burdensome in the tolerance management in the assemblage of the compressor.